Sieve roll for use in paper drying apparatus or the like

ABSTRACT

A sieve roll for use in paper drying apparatus wherein the tube of a shaft assembly carries two reinforced end walls whose innermost portions are welded to the tube and whose outermost portions are welded to the respective ends of elongated strips. The strips are disposed in planes which include the axis of the shaft assembly and they form a cylindrical sidewall spacedly surrounding the shaft assembly between the end walls. The space between the end walls receives rings which surround the shaft assembly, and have peripheral recesses for the strips. Each second ring is welded to the shaft assembly and to the strips, and the remaining rings are welded only to the strips. The cross section of each end wall is a right-angled triangle.

[ 1 Oct. 21, 1975 i 1 SIEVE ROLL FOR USE IN PAPER DRYING APPARATUS OR THE LIKE [75] Inventor: Hans Fliimig, Heidenheim, Brenz,

Germany [73] Assignee: J. M. Voith GmbH, Heidenheim,

Germany 22 Filed: Nov. 22, 1974 21 App]. No.: 526,369

[30] Foreign Application Priority Data Nov. 24, 1973 Germany 2358577 [52] US. Cl. 34/114; 34/122; 34/240; 29/121 R; 162/357; 162/372 [51] Int. Cl. F26B 11/02 [58] Field of Search ..34/110,111,115,1l31 14, 34/116-122, 240; 29/110, 116 R, 121 R, 123, 124, 125; 162/368, 357, 372, 373

Leckner' 34/115 Pennington 162/357 Primary ExaminerJohn J. Camby Assistant Examiner-James G. Yeung Attorney, Agent, or Firm-Michael S. Striker [57] ABSTRACT A sieve roll for use in paper drying apparatus wherein the tube of a shaft assembly carries two reinforced end walls whose innermost portions are welded to the tube and whose outermost portions are weldedto the respective ends of elongated strips. The strips are disposed in planes which include the axis of the shaft assembly and they form a cylindrical sidewall spacedly surrounding the shaft assembly between the end walls. The space between the end walls receives rings which surround the shaft assembly, andhave peripheral re cesses for the strips. Each second ring is welded to the shaft assembly and to the strips, and the remaining rings are welded only to the strips. The cross section References Cited of each end wall is a right-angled triangle.

UNITED STATES PATENTS 1,039,067 9/1912 Parker 162/372 10 3 Drawmg Flgures ll 3' I 7 80 l ,J 80 I I 6 8 I *I I I I I I I I I I I0 I I 9 US Patent 0a. 21, 1975 [III/Il/I/ Ill/l SIEVE ROLL FOR USE IN PAPER DRYING APPARATUS OR THE LIKE BACKGROUND OF THE INVENTION The present invention relates to apparatus for expelling moisture from webs of paper or other fibrous material, and more particularly to improvements in socalled sieve rolls which are utilized in such apparatus to effect or permit the flow of a gaseous fluid across successive increments of a running paper web.

It is already known to construct the periphery or sidewall of a sieve roll in such a way that the periphery includes enlongated strip-shaped members which extend in parallelism with the axis of the sieve roll. The strips are held apart by meandering auxiliary strips so that the sidewall resembles a hollow cylindrical honeycomb structure. Reference may be had to US. Pat. No. 3,303,576 or to German Offenlegungsschrift No. 1,461,112. The manufacture of such sidewalls is extremely costly, and the quantity of material which is needed to assemble the sidewall is very large. This is undesirable because the material of the strips is normally a highly corrosion-resistant and hence expensive metallic substance. Moreover, the weight of conventional sieve rolls is rather substantial which is undesirable when the sieve roll is to be rotated in response to contact with the running paper web.

SUMMARY OF THE INVENTION An object of the invention is to provide a relatively simple, lightweight and inexpensive but highly deformation-resistant sieve roll which can be used as a superior and cheaper substitute for presently known sieve rolls.

Another object of the invention is to provide a novel sidewall construction for use in the improved sieve roll.

A further object of the invention is to provide a lightweight and inexpensive sieve roll which is capable of resisting substantial externally applied bending, torsional and other stresses as well as pronounced residual internal stresses.

An additional object of the invention is to provide a sieve roll whose rigidity matches or exceeds that of heretofore known sieve rolls even though the quantity of material which is used for its assembly is only a small percentage of the quantity of material needed for the assembly of conventional sieve rolls.

Still another object of the invention is to provide novel end walls for use in the improved sieve roll and to provide novel and improved means for holding the strips which form part of the sidewall against sidwise movement toward or away from each other.

A further object of the invention is to provide a sieve roll which can be assembled in its entirety from commercially available components, such as strips, sheets or plates, disks, tubes and bar stock, and ,which can'be assembled by resorting to well known bonding techniques, especially to welding.

Another object of the invention isto provide a novel and improved sieve roll whose resistance to internal and/or external stresses is not dependent on its diameter and/or axial length.

The invention is embodied in a rotary sieve roll which is particularly suited for use in apparatus for drying prous paper webs, for example, running paper webs which issue from a Fourdrinier machine. The sieve roll comprises a shaft assembly, a pair of spaced-apart end walls which are concentric and rigid with the shaft assembly, a hollow cylindrical sidwall which is coaxial with the shaft assembly and includes a plurality of elongated strips having end portions rigid with the end walls and extending in parallelism with the axis of the shaft assembly, each of the strips being preferably located in a plane which includes the axis of the shaft assembly, and a plurality of rings surrounding the shaft assembly intermediate the end walls and being connected with the strips.

In accordance with a feature of the invention, each of the end walls has a substantially triangular crosssectional outline (the outline preferably resembles a rightangled triangle), as considered in a plane including the axis of the shaft assembly, and each such outline has an outer corner portion which is adjacent to the respective end portions of the strips and two additional corner portions which are adjacent to the shaft assembly. The outer sides of the end walls may be reinforced by radially extending solid or channel-shaped ribs or analogous stiffening elements.

At least some of the rings are preferably rigid with the shaft assembly and the preipheral surfaces of the rings are preferably formed with recesses for the strips.

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The improved sieve roll itself, however, both as to its construction and its mode of operation, together with additional features and advantages thereof, will be best understood upon perusal of the following detailed description of certain specific embodiments with reference to the accompanying drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic end elevational view of a paper drying apparatus which embodies the improved sieve roll;

FIG. 2 is a schematic axial sectional view of the sieve roll; and

FIG. 3 is a fragmentary sectional view as seen in the direction of arrows from the line III-III of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIEMENTS FIG. I shows a portion of an apparatus for drying a web ll of porous paper. The apparatus comprises an enclosure 3 which surrounds a sieve roll 2. The web 1 which issues from a papermaldng machine is trained over a first contact-drying cylinder 4, thereupon over the major part of the peripheral surface of the sieve roll 2, and finally over a second contact-drying cylinder 5. A suction chamber 6 has an inlet portion 6a which extends upwardly into the space between the cylinders 4, 5 and has a fluid-admitting opening immediately adjacent to that portion of the peripheral surface of sieve roll 2 which is not surrounded by the paper web ii. The suction chamber 6 draws air from the interior of the sieve roll 2 to thereby draw moisture from those increments of the paper web 1 which travel about the major part of periphery of the roll 2.. The sieve roll 2 is constructed in a manner as shown in FIGS. 2 and 3. Its periphery or sidewall is assembled of a plurality of relatively thin elongated metallic strips 7 each of which is parallel to the axis of the sieve roll 2 and each of which is preferably located in a plane including such axis. The end portions of the strips '7 are rigid with two end walls or heads 8 which, in turn, are rigid with a shaft assembly including an elongated cylindrical tube 9, two trunnions l0, and rings 13 which are welded to the tube 9 and to the respective trunnions. The axial length of the tube 9 equals or exceeds the combined axial length of the sidewall plus the two heads 8. The trunnions 10 have end portions extending outwardly beyond the respective ends of the tube 9.

Each of the end walls or heads 8 is a rigid deformation-resistant structure having a triangular crosssectional outline, as considered in a plane which includes the axis of the sieve roll 2. The outer corner portion of each triangle (preferably a right-angled traigle) is rigid with the respective end portions of the strips 7, and the other two corner portions of each triangle are rigid with the tube 9.

The sieve roll 2 further comprises two sets or groups of alternating rings 11 and 12 which are located in planes maing a right angle with the axis of the tube 9. The outer edge portions of the rings 11, 12 have recesses 11a, 12a which receive the adjacent portions of the strips 7. The inner diameters of the rings 12 equal or closely approximate the outer diameter of the tube 9 (see FIG. 3). On the other hand, the inner diameters of the rings 11 preferably substantialy exceed the outer diameter of the tube 9 so that the rings 11 are held in position only by the strips 7. All connections between the strips 7 and rings 11, 12, between the strips 7 and heads 8, between the rings 12 and tube 9, and between the rings 13 and trunnions l and tube 9 are preferably by welding. As a rule, the entire sieve roll 2 will consist of a corrosion-resistant metallic material, preferably stainless steel.

The composite shaft assembly 9, 10, 13 of the sieve roll 2 can be replaced by a greatly simplified shaft assembly, e.g., an assembly including the trunnions l0 and a tube whose diameter is much smaller than that of the tube 9 and whose end portions directly receive and are rigidly connected to the respective trunnions. The outer diameter of the tube 9 may be a small, fraction of the outer diameter of the sidewall including the strips 7.

Each of the end walls or heads 8 may comprise a circular plate which is welded to the strips 7 at its periphery and to the tube in the region of its central opening, and radially extending stiffening elements 8a (ribs or channels) which impart the necessary rigidity.

The strips 7 are resistant to bending in response to stresses which are applied to their outer edge faces, especially in the uppermost portion of the sieve roll 2, as viewed in FIG. 1. Such stresses may be applied to selected points or lengthwise of the entire outer edge faces of the strips 7. The end portions of the strips 7 transmit such stresses to the heads 8 which, in turn, transmit stresses to the rigid shaft assembly 9, 10, 13.

Torsional stresses are taken up by the shaft assembly 9, 10, 13 so that such stresses are not transmitted to other parts (7, 8, 11 and 12) of the sieve roll 2. Stresses acting in the circumferential direction of the sieve roll are taken up by the rings 11 and 12 which hold the strips 7 against sidwise movement relative to each other. It will be recalled that the peripheral surfaces of the rings 11 and 12 have recesses 11a, 12a for the strips 7 and that at least some of the rings (in the illustrated embodiment of the rings 12) are rigid with the tube 9 of the shaft assembly.

It will be seen that different types of stresses are taken up by different portions of the improved sieve roll. This renders it possible to construct the sieve roll of lightweight parts with substantial savings in expensive material. The feature that at least some (12) of the rings 11, 12 are rigid with the tube 9 insures that the sieve roll exhibits a pronounced resistance to circumferential stresses and that torque is transmitted uniformly to the shaft assembly 9, 10, 13 when the sieve roll 2 is caused to rotate in response to lengthwise movement of the paper web 1 or in response to transmission of torque to the trunnions 10. The shaft assembly can employ a tube with a relatively small diameter because the major part of bending stresses is taken up by the strips 7 and the remaining bending stresses which are transmitted to the tube by way of the rings (especially rings 12) are relatively small. The rings 11, 12 further insure that the sieve roll 2 can rotate without pronounced wobbling and they resist a cave-in of the periphery or sidewall of the sieve roll.

The provision of recesses 11a, 12a in the peripheral surfaces of the rings 11 and 12 serves an additional important purpose, namely the rings can counteract stresses which are not applied exactly radially of the sieve roll.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, be applying current knowledge, readily adapt it for various applications without omitting features which fairly constitute essential characteristics of the generic and specific aspects of my contribution to the art and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the claims.

What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.

1. A rotary sieve roll, particularly for use in apparatus for drying paper webs, comprising a shaft assembly; a pair of axially spaced end walls coaxial and rigid with said shaft assembly; a plurality of axially spaced rings surrounding said shaft assembly intermediate said end walls, said rings having outer edge portions: and a hollow cylindrical side wall including a plurality of circumferentially spaced elongated strips having end portions rigid with said end walls and extending in parallelism with the axis of said shaft assembly and intermediate portions connected with said outer edge portions of said rings, said strips defining openings with said rings and each strip being located in a plane including the axis of said shaft assembly, each of said end walls having a substantially triangular cross-sectional outline as considered in a plane including the axis of said shaft assembly, each of said outlines having an outer corner portion adjacent to the respective end portions of said strips and two additional comer portions adjacent to said shaft assembly.

2. A sieve roll as defined in claim 1, wherein at least some of said rings are rigid with said shaft assembly.

3. A sieve roll as defined in claim 1, wherein said outer edge portions are provided with recesses for said strips.

4. A sieve roll as defined in claim 1, wherein said end walls comprise stiffening elements extending substantially radially of said shaft assembly.

5. A sieve roll as defined in claim 1, wherein said shaft assembly comprises a tubular member which is coaxial with and is spacedly surrounded by said sidewall and a second member including trunnions coaxial with, received in and having portions extending beyond 8. A sieve roll as defined in claim 1, wherein said strips are welded to said end walls and said end walls are welded to said shaft assembly.

9. A sieve roll as defined in claim 1, wherein each of said end walls was a cross-sectional outline which is a right-angled triangle.

10. A sieve roll as defined in claim 1, wherein the diameter of said shaft assembly is a small fraction of the outer diameter of said sidewall. 

1. A rotary sieve roll, particularly for use in apparatus for drying paper webs, comprising a shaft assembly; a pair of axially spaced end walls coaxial and rigid with said shaft assembly; a plurality spaced rings surrounding said shaft assembly intermediate said end walls, said rings having outer edge portions; and a hollow cylindrical side wall including a plurality of circumferentially spaced elongated strips having end portions rigid with said end walls and extending in parallelism with the axis of said shaft assembly and intermediate portions connected with said outer edge portions of said rings, said strips defining openings with said rings and each strip being located in a plane including the axis of said shaft assembly, each of said end walls having a substantially triangular crosssectional outline as considered in a plane including the axis of said shaft assembly, each of said outlines having an outer corner portion adjacent to the respective end portions of said strips and two additional corner portions adjacent to said shaft assembly.
 2. A sieve roll as defined in claim 1, wherein at least some of said rings are rigid with said shaft assembly.
 3. A sieve roll as defined in claim 1, wherein said outer edge portions are provided with recesses for said strips.
 4. A sieve roll as defined in claim 1, wherein said end walls comprise stiffening elements extending substantially radially of said shaft assembly.
 5. A sieve roll as defined in claim 1, wherein said shaft assembly comprises a tubular member which is coaxial with and is spacedly surrounded by said sidewall and a second member including trunnions coaxial with, received in and having portions extending beyond the ends of said tubular member, said end walls being rigid with one of said members.
 6. A sieve roll as defined in claim 1, wherein said rings include a first group of rings which are rigid with said strips and with said shaft assembly and a second group of rings which are rigid with said strips and alternate with the rings of said first group.
 7. A sieve roll as defined in claim 1, wherein said shaft assembly, said strips, said end walls and said rings consist at least in part of a corrosion-resistant metallic material.
 8. A sieve roll as defined in claim 1, wherein said strips are welded to said end walls and said end walls are welded to said shaft assembly.
 9. A sieve roll as defined in claim 1, wherein each of said end walls was a cross-sectional outline which is a right-angled triangle.
 10. A sieve roll as defined in claim 1, wherein the diameter of said shaft assembly is a small fraction of the outer diameter of said sidewall. 